When US Vice-President Joe Biden finally got to comment on Iran in his recent speech at the policy conference of the American Israel Public Affairs Committee (AIPAC) in Washington D.C., he lowered his voice almost to a whisper: "Big nations," he said, "can't bluff. And presidents of the United States cannot and do not bluff. And President Barack Obama is not bluffing. He is not bluffing." Biden was of course referring to the ongoing Washington diatribes about deterrence versus prevention — and sought to reassure those who fear that the administration may hesitate to pre-empt Iran militarily if needs be.

The rhetorical effect of Biden's comments, delivered as if he was revealing a well-kept secret, put to rest the notion of a pusillanimous US executive with no appetite for war.

The administration's tough whispers may be reassuring to the adoring crowds of pro-Israel activists. And, to be fair, there is no reason to believe that Obama would hesitate if military prevention came to be the only way to stop Iran from acquiring nuclear weapons.

The problem for the President and his cabinet — even in the new incarnations of Secretary of State John Kerry and Secretary of Defense Chuck Hagel — is not whether there is a lack of will to launch a strike to prevent an Iranian nuclear bomb. The problem, as it has been for previous administrations, is to know when to act before it is too late.

Consider this — only six years ago, the Syrian dictator who has spent the last two years slaughtering his own people was busy building a replica of the North Korean Yongbyon nuclear reactor on the banks of the Euphrates. The US did not know its location — it was the Israelis who alerted the administration, as one learns from the recent, magisterial account of that episode in Elliott Abrams's essay, "Bombing the Syrian Reactor: The Untold Story", in the February issue of Commentary magazine.

Had it been left to American intelligence alone, Syria might have been where the freakish hermit Communist kingdom of North Korea is today. North Korean advances in nuclear weapons were not exactly forecast with Swiss-watch precision by the CIA.

And when the US showed up in Tripoli in 2004 to collect Muammar Gaddafi's nuclear arsenal, which the Libyan dictator had traded in for his regime's safety (a bad bargain for him, eventually — see North Korea by contrast), its team was surprised by the difference in size between what they had expected and what they were given. That difference is a measure of how blind Western intelligence is to such threats.